1. Field of the Invention
This invention relates to an electronic fuel supply device for automotive engine and more particularly to a fuel supply device for a multicylinder engine which comprizes a vortex flow sensor for sensing the amount of suction air into the engine and a fuel metering device including electro-magnetic valves driven for a predetermined time in synchronism with the frequency output from the vortex flow sensor and a control valve operable to limit the flow of fuel through said electro-magnetic valves, the fuel being supplied to fuel injection valves in the respective cylinders in an amount metered by the fuel metering device.
2. Description of the Prior Art
It is well known that a vortex flow sensor affords a frequency output signal corresponding to the vortex speed (or the number of generated vortices) which is proportional to the flow of suction air being measured. It is thus contemplated to supply to the engine an amount of fuel referenced to the frequency output of the vortex sensor which is proportional to the suction air flow. The flow of suction air for a 2000 cc engine ranges from about 2 liters/sec. for idling to about 85 liters/sec. for a maximum speed which is 40 to 45 times the fuel flow for idling. On the other hand, the injection frequency of the fuel injection electro-magnetic valves has the maximum value of 200 to 250 Hz as a practical limit. The injection frequency for idling of the same engine should be 10 Hz or more; otherwise, the vehicle may be subjected to torque fluctuations. Thus, the frequency for the magnetic valve is changed in a range of from a minimum to about 20 times such a minimum. The total range of variations in the suction air flow (40 to 45 times) may not be covered by a single electro-magnetic valve designed to inject fuel in a timed relationship with the vortex speed. For such case, a plurality of electro-magnetic fuel injection valves are employed. If such fuel injection valves are to be mounted to each cylinder of a multi-cylinder engine, a plurality of such injection valves will be required for each cylinder, resulting in a complicated structure and prohibitive cost.